A small stem from a hibiscus plant was placed in a nutrieent medium, and it developed into a new plant. The new plant was reproduced

Analyze the question: A piece of stem (a vegetative part) was cut and placed in a nutrient medium, where it grew into a whole new plant. We need to say what type of reproduction this is and how the new plant's genotype compares with the parent's.

Concept:

• Sexual reproduction involves gametes (sex cells) from two parents fusing in fertilisation. This produces genetic variation, so the offspring differ from the parents.
• Asexual reproduction involves only one parent. No gametes or fertilisation are involved, and the new plant develops by mitosis from body (somatic) cells.
• Mitosis produces daughter cells that are genetically identical to the parent cell. So the offspring is a clone.
• Growing a plant from a cutting or stem in a nutrient medium is vegetative propagation, a form of asexual reproduction. In a laboratory it is also called tissue culture.

Solution:

1. A stem piece was used and no seeds, flowers or gametes were involved. So the reproduction is asexual. This rules out B and D.
2. Asexual reproduction uses mitosis only, so there is no mixing of genes from two parents. The new plant therefore has the same genotype as the parent. This rules out A.
3. That leaves C: asexually with the same genotype as the parent plant.

Answer: C

Tip: If a question describes a new plant growing from a stem, leaf, root or tissue piece, think "one parent, mitosis, clone, same genotype." Only seeds from fertilisation give sexual reproduction with variation. Examples to remember are cassava stem cuttings, sugarcane, yam tubers and Bryophyllum leaves.